2022-01-26 15:22:34

by Badhri Jagan Sridharan

Subject: [PATCH v2 1/2] usb: typec: tcpm: Do not disconnect while receiving VBUS off

With some chargers, vbus might momentarily raise above VSAFE5V and fall
back to 0V before tcpm gets to read port->tcpc->get_vbus. This will
report a VBUS off event causing TCPM to transition to SNK_UNATTACHED
where it should be waiting in either SNK_ATTACH_WAIT or SNK_DEBOUNCED
state. This patch makes TCPM avoid vbus off events while in
SNK_ATTACH_WAIT or SNK_DEBOUNCED state.

Stub from the spec:
"4.5.2.2.4.2 Exiting from AttachWait.SNK State
A Sink shall transition to Unattached.SNK when the state of both
the CC1 and CC2 pins is SNK.Open for at least tPDDebounce.
A DRP shall transition to Unattached.SRC when the state of both
the CC1 and CC2 pins is SNK.Open for at least tPDDebounce."

[23.194131] CC1: 0 -> 0, CC2: 0 -> 5 [state SNK_UNATTACHED, polarity 0, connected]
[23.201777] state change SNK_UNATTACHED -> SNK_ATTACH_WAIT [rev3 NONE_AMS]
[23.209949] pending state change SNK_ATTACH_WAIT -> SNK_DEBOUNCED @ 170 ms [rev3 NONE_AMS]
[23.300579] VBUS off
[23.300668] state change SNK_ATTACH_WAIT -> SNK_UNATTACHED [rev3 NONE_AMS]
[23.301014] VBUS VSAFE0V
[23.301111] Start toggling

Fixes: f0690a25a140b8 ("staging: typec: USB Type-C Port Manager (tcpm)")
Cc: [email protected]
Signed-off-by: Badhri Jagan Sridharan <[email protected]>
---
Changes since v1:
- Fix typos stated by Guenter Roeck.
---
drivers/usb/typec/tcpm/tcpm.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/usb/typec/tcpm/tcpm.c b/drivers/usb/typec/tcpm/tcpm.c
index 59d4fa2443f2..3bf79f52bd34 100644
--- a/drivers/usb/typec/tcpm/tcpm.c
+++ b/drivers/usb/typec/tcpm/tcpm.c
@@ -5156,7 +5156,8 @@ static void _tcpm_pd_vbus_off(struct tcpm_port *port)
case SNK_TRYWAIT_DEBOUNCE:
break;
case SNK_ATTACH_WAIT:
- tcpm_set_state(port, SNK_UNATTACHED, 0);
+ case SNK_DEBOUNCED:
+ /* Do nothing, as TCPM is still waiting for vbus to reach VSAFE5V to connect */
break;

case SNK_NEGOTIATE_CAPABILITIES:
--
2.35.0.rc0.227.g00780c9af4-goog

2022-01-26 17:40:49

by Guenter Roeck

Subject: Re: [PATCH v2 1/2] usb: typec: tcpm: Do not disconnect while receiving VBUS off

On 1/25/22 18:00, Badhri Jagan Sridharan wrote:
> With some chargers, vbus might momentarily raise above VSAFE5V and fall
> back to 0V before tcpm gets to read port->tcpc->get_vbus. This will
> report a VBUS off event causing TCPM to transition to SNK_UNATTACHED
> where it should be waiting in either SNK_ATTACH_WAIT or SNK_DEBOUNCED
> state. This patch makes TCPM avoid vbus off events while in
> SNK_ATTACH_WAIT or SNK_DEBOUNCED state.
>
> Stub from the spec:
> "4.5.2.2.4.2 Exiting from AttachWait.SNK State
> A Sink shall transition to Unattached.SNK when the state of both
> the CC1 and CC2 pins is SNK.Open for at least tPDDebounce.
> A DRP shall transition to Unattached.SRC when the state of both
> the CC1 and CC2 pins is SNK.Open for at least tPDDebounce."
>
> [23.194131] CC1: 0 -> 0, CC2: 0 -> 5 [state SNK_UNATTACHED, polarity 0, connected]
> [23.201777] state change SNK_UNATTACHED -> SNK_ATTACH_WAIT [rev3 NONE_AMS]
> [23.209949] pending state change SNK_ATTACH_WAIT -> SNK_DEBOUNCED @ 170 ms [rev3 NONE_AMS]
> [23.300579] VBUS off
> [23.300668] state change SNK_ATTACH_WAIT -> SNK_UNATTACHED [rev3 NONE_AMS]
> [23.301014] VBUS VSAFE0V
> [23.301111] Start toggling
>
> Fixes: f0690a25a140b8 ("staging: typec: USB Type-C Port Manager (tcpm)")
> Cc: [email protected]
> Signed-off-by: Badhri Jagan Sridharan <[email protected]>

Why did you drop the Reviewed-by/Acked-by tags ?

Guenter

> ---
> Changes since v1:
> - Fix typos stated by Guenter Roeck.
> ---
> drivers/usb/typec/tcpm/tcpm.c | 3 ++-
> 1 file changed, 2 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/usb/typec/tcpm/tcpm.c b/drivers/usb/typec/tcpm/tcpm.c
> index 59d4fa2443f2..3bf79f52bd34 100644
> --- a/drivers/usb/typec/tcpm/tcpm.c
> +++ b/drivers/usb/typec/tcpm/tcpm.c
> @@ -5156,7 +5156,8 @@ static void _tcpm_pd_vbus_off(struct tcpm_port *port)
> case SNK_TRYWAIT_DEBOUNCE:
> break;
> case SNK_ATTACH_WAIT:
> - tcpm_set_state(port, SNK_UNATTACHED, 0);
> + case SNK_DEBOUNCED:
> + /* Do nothing, as TCPM is still waiting for vbus to reach VSAFE5V to connect */
> break;
>
> case SNK_NEGOTIATE_CAPABILITIES:

2022-01-26 18:01:52

by Badhri Jagan Sridharan

Subject: Re: [PATCH v2 1/2] usb: typec: tcpm: Do not disconnect while receiving VBUS off

My bad ! Apologies .. fixing it in V3..


On Tue, Jan 25, 2022 at 7:34 PM Guenter Roeck <[email protected]> wrote:
>
> On 1/25/22 18:00, Badhri Jagan Sridharan wrote:
> > With some chargers, vbus might momentarily raise above VSAFE5V and fall
> > back to 0V before tcpm gets to read port->tcpc->get_vbus. This will
> > report a VBUS off event causing TCPM to transition to SNK_UNATTACHED
> > where it should be waiting in either SNK_ATTACH_WAIT or SNK_DEBOUNCED
> > state. This patch makes TCPM avoid vbus off events while in
> > SNK_ATTACH_WAIT or SNK_DEBOUNCED state.
> >
> > Stub from the spec:
> > "4.5.2.2.4.2 Exiting from AttachWait.SNK State
> > A Sink shall transition to Unattached.SNK when the state of both
> > the CC1 and CC2 pins is SNK.Open for at least tPDDebounce.
> > A DRP shall transition to Unattached.SRC when the state of both
> > the CC1 and CC2 pins is SNK.Open for at least tPDDebounce."
> >
> > [23.194131] CC1: 0 -> 0, CC2: 0 -> 5 [state SNK_UNATTACHED, polarity 0, connected]
> > [23.201777] state change SNK_UNATTACHED -> SNK_ATTACH_WAIT [rev3 NONE_AMS]
> > [23.209949] pending state change SNK_ATTACH_WAIT -> SNK_DEBOUNCED @ 170 ms [rev3 NONE_AMS]
> > [23.300579] VBUS off
> > [23.300668] state change SNK_ATTACH_WAIT -> SNK_UNATTACHED [rev3 NONE_AMS]
> > [23.301014] VBUS VSAFE0V
> > [23.301111] Start toggling
> >
> > Fixes: f0690a25a140b8 ("staging: typec: USB Type-C Port Manager (tcpm)")
> > Cc: [email protected]
> > Signed-off-by: Badhri Jagan Sridharan <[email protected]>
>
> Why did you drop the Reviewed-by/Acked-by tags ?
>
> Guenter
>
> > ---
> > Changes since v1:
> > - Fix typos stated by Guenter Roeck.
> > ---
> > drivers/usb/typec/tcpm/tcpm.c | 3 ++-
> > 1 file changed, 2 insertions(+), 1 deletion(-)
> >
> > diff --git a/drivers/usb/typec/tcpm/tcpm.c b/drivers/usb/typec/tcpm/tcpm.c
> > index 59d4fa2443f2..3bf79f52bd34 100644
> > --- a/drivers/usb/typec/tcpm/tcpm.c
> > +++ b/drivers/usb/typec/tcpm/tcpm.c
> > @@ -5156,7 +5156,8 @@ static void _tcpm_pd_vbus_off(struct tcpm_port *port)
> > case SNK_TRYWAIT_DEBOUNCE:
> > break;
> > case SNK_ATTACH_WAIT:
> > - tcpm_set_state(port, SNK_UNATTACHED, 0);
> > + case SNK_DEBOUNCED:
> > + /* Do nothing, as TCPM is still waiting for vbus to reach VSAFE5V to connect */
> > break;
> >
> > case SNK_NEGOTIATE_CAPABILITIES:
>